Perhaps he didn't installed cups, pulseaudio, samba, conky, compiz which increase lots of ram usages in total.Since he didn't show any desktop image so we can't tell what stuff that he pre-installed that make it light.if resize panel into a small box it'll reduce a lot. However at least I can see LXDE getting heavier than Xfce from his testing.

if you look at the above screenshot, you will notice that if you subtract "available" from "total" (in the output of free) you will get exactly the 901 MB claimed by gnome-system-monitor.

man of free wrote:available Estimation of how much memory is available for starting new applications, without swapping. Unlike the data provided by the cache or free fields, this field takes into account page cache and also that not all reclaimable memory slabs will be reclaimed due to items being in use (MemAvailable in /proc/meminfo, avail‐ able on kernels 3.14, emulated on kernels 2.6.27+, otherwise the same as free)

silvaf6 wrote:Are you saying that for some reason my os is caching more stuff in ram? Im ok with it and my system is fast anyway, just found it odd that gsm had a biggest increase of ram usage than the average.

He's saying that, as far as I can gather, gsm lists the amount of used and cached memory, whereas free -m does not list the cached memory usage.

There's a saying in tech communities that "unused RAM is wasted RAM" which is upheld by some while being sneered at by others - largely gamers who have 16GB-64GB of RAM, much of which will likely never be used. Personally I am on 5GB of RAM, 3GB SWAP and I have never maxed out.